For me Alien 3 is a case of a director making lemonade out of lemons. As its own film its pretty good, but as a follow up to Alien they just chose a horrible premise.
But Fincher's direction was masterful. What a mood! And the cinematography was beautiful, even if it was a little too "brown." I'm just kind of fascinated with the picture. Its unpleasant yet strangely compelling. Depressing, but with a surprisingly high rewatch value. Quite the unique animal.
Another reason I'm partial to it is I've owned a bootleg workprint of it for about five years, with *no* musical score and a lot of scenes that ended up in the recent special edition.
Watching the movie without music makes the whole thing play like you're watching real events that were captured by surveillance cameras at a futuristic prison. No manufactured tension or drama, just people emoting and running for their lives. A very unique cinematic experience.